Rifling for firearms



A. B. LASHLEY.

RIFLING FOR FIREARMS.

APPLICATION EILED JUNE 26' 1916-.

Patented Mar. 30,1920.

- 2 SHEETSSHEET' I.

A. B. LASHLEY.

RIFLING FOR FIREARMS.

APPLICATION FILED JUNE 26, I916.

35,444; Patented Mar. 30,1920.

2 SHEETS-SHEET 2.

ARIN OLD B. LASHLEY, OF SALCHACKET, TERRITORY OF ALASKA.

nIrLINe'FoR FIREARMS.

Specification of Letters latent.

Patented Mar. so, 1920.

Application filed June 26, 1916. Serial No. 105,944.

To all whom it may concern:

Be it known that I, ARNOLD B. LASHLEY, a citizen of the United States, residing at Salchacket, Territory of Alaska, have invented certain new, and useful Improvements in Rifiing for Firearms, of which the following is a specification.

To obtain great accuracy and penetration at long-range, it is necessary to provide a relatively high pitch to the rifling of a firearm and high velocity to the projectile. At

the same time, the rifling must be of such a character that the j acket' of the bullet will not be stripped, due to its .overriding the lands of the rifling, or, mother wordsycross the grooves and not rotate. Such faul-ls often exist when the rifling is of high pitch and the desired muzzle velocity is intended to be relatively great. If the rifling is of such a character that merely a narrow, deep scoring of the jacket of the bullets results, the lead core will be entered and the equilibrium of the projectile will be overcome.

Excessive friction of the projectile on the rifling when the latter produces the foregoing defects in the acket and'projectile core, causes the bullet to key-hole or dumdum and,- in extreme cases to lose its equilibrium and entirely explode.

My object is to provide an improved rifling which will insure against any 6f the foregoing defectsand impart to the bullet the requisite rotation without disturbing its equilibrium and with a minimum degree of friction so that the rifling maybe of high pitch and the charge adapted to impart high velocity to the projectile without any danger of excessive heat, undue strain on the rifling, or overriding of the lands in any manner which we .ld interfere with the rotation of the bullet and, consequently, to obtain great accuracy and greatly increase the life of the firearm.

My rifling may have either square-cut or semi-U-shaped lands and in all cases. the grooves and the lands are each uniform in depth throughout the entire length of the bore of the firearm. My improved rifling has lands and grooves so spaced and of such dimensions in both width and depth as adapt them to form relatively deep, broad and well-defined creases or channels in the projectile and, at the same time, take care of, or accommodate, the expansion in diameter of the projectile which results from the formation of the creases and the corresponding contraction of the diameter of the pro jectile in the vicinity of the creases. I thus overcome a defect heretofore existing, due to failure of rifling to provide for therexpansion in diameter of the projectile and its jacket into. the grooves of the rifling as a result of the formation of the creases by j the lands of said rifling. As these changes are brought about when the bullet is first fired in the breech of the bore, the bullet has no portion which is crowded over the lands to interfere with its rotation during the remainder of its travel through the bore and consequently, there is no stripping, but on the contrary, the depth of the creases formed in the jacket of the projectile causes the latterto directly rotate by reason of its correct cooperation with the lands and grooves of the rifling. The result is greater accuracy and penetration as the rifling may be of such high pitch and the charge of such character that great rotation and velocity may he obtained-elements necessary to accuracy and penetration at long range.

In the accompanying drawings:

Figure l is a longitudinal section through a rifle barrel provided with my rifling;

Fig. 2, an enlarged view looking toward the muzzle, showing the semi-U-shaped or rounded lands;

Fig. 3, a similar lands; 1

Fig. 4, an end view of the projectile with the creases formed therein by the rifling of i v Fig. 5, a similar view showing the creases formed by'the rifling ofFig. 3; and

Fig. 6, a detail perspective illustratin the expansion from the normal diameter of the projectile and its jacket which occurs after firing;

Fig. 7, an enlarged detail cross-section showing rifling having square-cut lands, with dotted line showing of the true bore, the normal circle of the projectile, and their diameters, to illustrate the action of the rifling of Fig. 3;

Fig. 8, a similar View, certain parts of the lands being shaded to illustrate the action on the projectile; and

Fig. 9, a view like Fig. 7, showing semi- U-sha-ped or rounded lands, to illustrate the action of the lands of Fig. 2.

Referring first to Figs. 1 and 2, the barrel 1 of the firearm has rifling for the enview showing square-cut tire length of its bore from the breech to the muzzle and occupying the entire periphery of the bore, composed of equi-distantly spaced rounded or semi-U-shaped lands 2, and grooves 3. The lands 2 are narrow in relation to the width of the grooves 3, but all the lands are of the same height and all are uniform in height from the breech to the muzzle. The grooves 3 are of uniform depth from the breech to the muzzle, and they are of such width, relative to the width of the lands 2, that they are adapted to accommodate the expansion in diameter of the projectile between the deep creases formed by the lands 2. The compression on the projectile and its jacket caused by the relatively deep lands 2, results in a corresponding increase in the diameter of the projectile which increase 1s accommodated by the relatively wide and deep grooves 3. This is illustrated in Fig. 6, where the projectile is shown at 4 whose original diameter, previous to firing, is shown at 5 and whose increased or expanded diameter is as shown at 6 intermediate the deep creases 7 which are formed by the deep lands 2. The increased diameter shown at 6 intermediate the respective grooves 7 represents those parts of the projectile which expand into the wide and deep grooves 3 of the rifiing. The resulting expansion of the projectile is, therefore, compensated for without any danger of the jacket overriding the lands or the jacket being cut through to allow the lead inside to expand or cause the true general cylindrical shape of the projectile to be impaired. While the lands 2 are relatively deep and broad, they are narrow in relation to the grooves 3 to permit full accommodation in said grooves 3 for the expanded parts of the projectile and its jacket.

he projectile, having been fired, immediately becomes creased in the region of the breech of the firearm, as shown in Figs. 4

and 6, and it thereupon rotates, without hindrance during the remainder of its travel through the bore and without engendering more than a minimum of friction and enabling a high pressure charge of explosive to be used where the pitch or twist of the rifling is relatively great. Consequently, high velocity and relatively rapid rotation may be imparted to the projectile when my rifling is used, without danger of undue heating of the firearm, even when rapidly fired, or causing the bullet to key-hole or dum-dum, as the friction is minimized.

The rifling of Fig. 3 is the same as that of Fig. ,2, except that the lands 2 are square-cut.

Fig. t shows the appearance of the end of a projectile fired through a firearm having the rifling of Fig. 2, and Fig. 5 represents the projectile after being fired through rifiing such as shown in Fig. 3.

In both these instances the creases 7 or 7* are relatively deep so that the projectile will rotate truly with the rifle and not strip across the lands.

The jacket appears at 8 and the lead core at 9.

Referring to Figs. 7, 8, and 9: the circle of the true bore is shown at 3; the diameter of said circle being shown at 3", and the center of the circle at 3. The circle of the normal condition or size of the projectile is shown at 3, whose diameter appears at 3 The space in the bottoms of. the grooves of the rifling comprehended between the circle of the normal size of the pro'ectile and the circle of the grooves of the rifling is designated 3. The diameter of the circle comprehending the bottoms of the grooves, ap-

pears at3 In Figs. 7 and 8, the square faces of the lands are designated 3 and in Fig. 9, the rounded faces of the lands appear at 3.

Those portions of the lands comprehended between the circles 3 and 3 are shaded and marked 3.

V The faces 3 are at right angles to a diameter 3 of the true bore.' The sides of the lands, 3", lie in diameters correspondin to the diameter '3. The lands are, there ore, square-cut as to sides and faces, though the corners of the lands of Figs. 2 and 9 may be rounded as shown at 3. p

The shaded parts 3, Fig. 8 represent the depth and width of the creases 7' made in the projectile; the same creases, except for rounded formation, would be made by the lands of Figs. 2 and 9.

As the bullet or projectile has a jacket 8 which is-of soft steel or cupro-nickel, it becomes creased by the lands when the cartridge is fired and the underlying soft metal 9 is displaced and forced into the three spaces 3 between the respective lands and comprehended by the circles 3 and the bottoms of the grooves. For instance, in a 7- millimeter caliber bullet, the expansion of the diameter, when the cartridge is fired, is about one-third, or, say, of a millimeter.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:. t

1. The combination with a-firearm having a rifling comprising lands and grooves, of an expansible projectile adapted for use with said firearm, said projectile having a normal diameter which is greater than the true bore of the rifiing and less than the diameter across the bottoms of the grooves, said lands, grooves, and projectile being relatively proportioned to effect relatively deep creases in the surface of the projectile where engaged by the lands and the expansion of the projectile into the grooves to fill the grooves completely due solely to the displacement of the metal by the lands with out stripping or overriding the lands when the projectile is fired.

The combination with a firearm having a rifling comprising alternating lands and grooves, the lands having their sides lying in diameters of the bore and being provided with flat faces disposed at right angles to diameters of the bore, of an expansible projectile adapted for use with said firearm, said projectile having a normal diameter which is greater than the true bore of the rifling and less than the diameter across the bottoms of the grooves, said lands, grooves, and projectile being relatively proportioned to effect relatively deep creases in the surface of the projectile where engaged by the lands and the expansion of the projectile into the grooves to fill the grooves completely due solely to the displacement of the metal by the lands without stripping or over-riding the lands when the projectile is fired;

3. The combination with a firearm having a rifling comprising alternating lands and grooves,- the lands having relatively broad faces and being of relatively great depth and the grooves being proportionately Wide and deep, of an expansible projectile adapted for use with said firearm, said projectile having a normal diameter which is greater than the true bore of the rifiing and less than the diameter across the bottoms of the grooves, said lands, grooves, and rojectile being relatively proportioned to 'e ect rela-' tively deep creases in the surface of the projectile where engaged by the lands and the expansion of the projectile into the grooves to fill the grooves completely due solely to the displacement of the metal by the lands without stripping or over-riding the lands when the projectile is fired.

In testimony whereof I hereunto aflix my signature.

ARNOLD B. LASHLEY. 

